Skip to main content

Full text of "Circuits"

See other formats


Introduction to Electronics: The Diode 



Make] Projects 

hhiiilH ho/ 1 !/ tuMaal/ chare r\icf*f\\tat* 



build, hack, tweak, share, discover,- 



Introduction to Electronics: The 



Diode 



Written By: KRA5H 



TOOLS: 



Snap Circuits Extreme 750 set (1) 
available at your local RadioShack store 



PARTS: 



Base Grid (11" x 7.7") # 6SC BG (1) 
Battery Holder (2-AA^ # 6SC B1 (1) 
6V Lamp Socket (With Bulb) # 6SC L2 

in 

Slide Switch # 6SC S1 (1) 
Conductor with 2-snaps # 6SC 02 (4) 
Conductor with 3-snaps # 6SC 03 (1) 
Diode 1N4001 #6SCD3(1) 
RedLED#6SCD1 (1) 
100 ohm Resistor # 6SC R1 (1) 



© Make Projects 



www.makeprojects.com 



Page 1 of 9 



Introduction to Electronics: The Diode 



Step 1 — Introduction to Electronics: The Diode 




• According to Wikipedia , "The most 
common function of a diode is to 
allow an electric current to pass in 
one direction (called the diode's 
forward direction), while blocking 
current in the opposite direction 
(the reverse direction). Thus, the 
diode can be viewed as an 
electronic version of a check 
valve." 



Step 2 



Surface of water 




• What is a check valve? You can 
think of it like a ping pong ball cage 
snorkel. 

• When the ping pong ball cage is 
above the surface of the water, the 
ping pong ball is at the bottom of 
the cage and you can breathe 
through the snorkel. As the cage 
moves below the surface of the 
water, the ping pong ball floats up 
until it blocks the opening of the 
snorkel blocking any water from 
getting into the snorkel. 



© Make Projects 



www.makeprojects.com 



Page 2 of 9 



Introduction to Electronics: The Diode 



Step 3 




• The diode has a number of 
applications in electronic circuits. 
One application you may be 
familiar with is a rectifier. A 
rectifier converts alternating 
current (AC) to direct current (DC). 
Alternating current periodically 
changes direction while direct 
current only flows in one direction. 

• To use a diving analogy, imagine a 
scuba diver. Since scuba divers 
carry their air with them they can 
still breathe whether their heads 
are above water or underwater. 
You can imagine a scuba diver 
surfacing and diving repeatedly and 
the path the diver traces forms a 
sine wave. 



© Make Projects 



www.makeprojects.com 



Page 3 of 9 



Introduction to Electronics: The Diode 



Step 4 




• The sine wave is what alternating 
current looks like. At the crest, or 
top of the wave you might measure 
+5 volts and at the trough, or 
bottom of the wave you might 
measure -5 volts. At the line 
through the middle you would 
measure volts. 



Step 5 











r^\ r^\ 








Surface of water fli^^H 




Surface of water 




(% i) 




(1 1 i) 

















• Let's say we wanted to use a diode as a rectifier to convert alternating current to direct 
current. 

• Now imagine our snorkeler surfacing and diving. While the ping pong ball cage on the 
snorkel is above the water the snorkeler can take a breath of air. 

• When the cage sinks below the water the ping pong ball blocks the water from getting into 
the snorkel and the snorkeler has to hold his or her breath until surfacing again to exhale 
and take another breath. 



© Make Projects 



www.makeprojects.com 



Page 4 of 9 



Introduction to Electronics: The Diode 



Step 6 




• Like the ping pong ball acts as a 
check valve to prevent water from 
getting into the snorkel, the diode 
acts as a check valve to block 
current from flowing in the reverse 
direction. 

• The diagram is what the voltage 
will look like when the alternating 
current is converted to direct 
current. 

• You would measure from volts to 
+5 volts then back to volts. You 
wouldn't be able to measure the 
voltage in the reverse direction 
from volts to -5 volts because it 
is being blocked by the diode. 
When the alternating current cycles 
back to volts you would then be 
able to measure the voltage from 
volts to +5 volts and then back to 
volts. 



© Make Projects 



www.makeprojects.com 



Page 5 of 9 



Introduction to Electronics: The Diode 



Step 7 







: 




. 


i i 




i! 


1 i° 


H. 










fev 


















fcC .•;-;» 




















T- i 


j -■ 


L' 








^Ti 


F •w-fJP 














L 


















^ 




















• Now we can see what happens when we reverse the diode. Build the circuit shown with the 
diode in the reverse direction. The photos show the step-by-step build. When you're done 
building the circuit, slide the switch (S1) from the off position to the on position. 

Wei I... nothing happens. 

• In a DC (direct current) circuit, the electricity flows in one direction. 

• When you switch the circuit on you can think of it as current flowing from the positive side 
of the battery (marked with a "+" sign) to ground (marked with a "-" sign) and you can think 
of the flow of current as kinetic energy that can be used to do useful work such as light up 
an incandescent bulb. 

• So, when you switch the circuit on, why doesn't the light bulb light up? Because the diode 
is blocking the flow of electrcity like the ping pong ball on the snorkel blocking the water 
from getting in. 



© Make Projects 



www.makeprojects.com 



Page 6 of 9 



Introduction to Electronics: The Diode 



Step 8 




• Switch the circuit off and change the diode from the reverse direction to the forward 
direction. Then switch the circuit on and the light bulb lights up. 

• Now the diode is no longer blocking the flow of electricity and current can flow from the 
positive (+) terminal on the battery through the circuit to the ground (-) terminal on the 
battery. 



Step 9 




• This is the electronic symbol for 
the diode so that you will be able to 
recognize it on an electronic 
schematic. 

• When a positive voltage is applied 
to the terminal on the left and a 
negative voltage to the terminal on 
the right, the diode is "forward 
biased" and current wiill flow 
through it. 

• If the polarity is reversed, the diode 
is "reverse biased" and no current 
will flow. 



© Make Projects 



www.makeprojects.com 



Page 7 of 9 



Introduction to Electronics: The Diode 



Step 10 







! ; 


| 




> 6 


l| 




- 


1 



























£■ 








I^^^Sfi^jti™? - 






= 


" 












_r 


°. 




H 






R 








4 




































E 






















F 






















<j 





























• Now let's take a look at the Light Emitting Diode (LED). 

• The light emitting diode functions much the same as an ordinary diode, but also lights up 
when enough current is flowing through it in the forward direction (forward-biased). LEDs 
are often used in electronic devices to indicate that the device is switched on, but they can 
serve many practical purposes. 

• Build the circuit shown. The photos demonstrate the step-by-step build. 

• When you switch the circuit on. ..again, nothing happens. Why doesn't the light LED light 
up? Because the LED is reversed and blocking the flow of electrcity. 

Step 11 





i : 


i ; 


s < 


! 


1 i 




1 


ii 


10 


A 




















B 








BV 


\ AAA Ry 


[H3K 
















C 






WA 


U 






pm 




D 






P] 


■E9K 


SLIDE SWITCtT 


















E 




















F 
G— 






















• Switch the circuit off and turn the LED around. 

• Now you can switch the circuit on and with the LED in the forward-biased direction, it lights 
up. 



© Make Projects 



www.makeprojects.com 



Page 8 of 9 



Introduction to Electronics: The Diode 



Step 12 





"i. 





• This is the electronic symbol for 
the LED so that you will be able to 
recognize it on an electronic 
schematic. 



This document was last generated on 201 2-1 0-30 07:21 :59 PM. 



© Make Projects 



www.makeprojects.com 



Page 9 of 9